This category D study is designed to test the safety, pharmacokinetics, and efficacy of a liposomal amikacin preparation in stable patients with cystic fibrosis who are colonized with gram-negative bacteria. The GCRC Endoscopy Suite is used to perform serial bronchoalveolar lavage studies to determine concentration of the drug in the alveoli. The pharmacokinetic portion of the study also is well suited to the GCRC. Preliminary data on this study are not yet available for analysis.